1. Field of the Invention
This invention relates to motorized wheelchairs and, more particularly, to wheelchair mounted control apparatus for enabling disabled persons to control the operation of a motorized wheelchairs by means of voice commands.
2. Description of the Prior Art
Particularly for persons paralyzed from the neck down the problem of operating or controlling a motorized wheelchair has been formidable. Conventional powered wheelchair control systems employ a "joy stick" or other control means which must be operated by the hands of the invalid.
Various methods have been proposed for allowing a quadriplegic to control a motorized wheelchair. For example, systems have been proposed which allow the quadriplegic to control a wheelchair by means of head or eye movements. Eye movement systems suffer the disadvantage of being sensitive to the intensity of ambient light. Head movement systems, on the other hand, require somewhat unnatural movements of the head in order to control the chair. These movements may be psychologically undesirable for an invalid who desires to appear as "natural" as possible to the outside world. Both of the above systems provide only limited control capability. For example, neither system provides the capability to make small adjustments in the direction of travel of the chair which are necessary to correct the "drift" which occurs when the chair travels over irregular terrain.
Breath-controlled wheelchair systems are also known in the art. In these systems the invalid controls the chair by sucking or blowing into one or more tubes. The degree of control which can be provided is limited by the number of tubes used. Thus, a high degree of control would require a large number of tubes, and such a system would be too complex for effective operation by the invalid.
A voice controlled wheelchair described by Clark, et al (Arch. Phys. Med. Rehabil., Vol. 58, pp. 169-75, 1977) includes provisions for slowly accelerating the chair to the left or to the right while the chair is traveling in a forward direction. No provision is made, however, for causing small positioning movements of the chair while it is at rest or traveling in a reverse direction. This limits the ability of the operator to make small positioning movements of the chair in restricted areas.
It is an object of the present invention therefore to provide a powered wheelchair control apparatus which allows a quadiplegic to exercise a high degree of control over the wheelchair.
It is a further object of the present invention that the invalid is not required to make any unnatural movements of the body in order to control the wheelchair.
It is yet a further object of the invention to provide apparatus for enabling the wheelchair operator to make changes in the speed or direction of travel of the wheelchair while the chair is or is not in motion.
It is a still further object of the invention to provide apparatus for accomplishing such changes in the speed or direction of travel of the chair in small incremental steps.
It is a still further object of the invention to provide apparatus to prevent the performance of those changes in the direction of travel of the wheelchair which could prove hazardous to the operator.